1. Field of the Invention
The present invention relates to a trigger for regenerative substances, and particularly relates to a trigger for regenerative substances which causes liquid regenerative substances in a supercooled state to begin crystallization.
2. Description of the Prior Art
As a regenerative substance, a substance such as 3-hydrates of sodium acetate has been conventionally used, taking advantage of its character to absorb or radiate a latent heat, due to phase changes between freezing and melting. After such a regenerative substance melts by heat and when it is cooled down to its freezing point, it begins crystallizing and simultaneously radiating a latent heat, and enters into a state of heat generation. However, the regenerative substance sometimes does not crystallize and reaches a supercooled state even if it is cooled down to its freezing point or a lower temperature.
As an example method for preventing such a supercooled state of the above-described regenerative substance, it is known that a crystalline nucleus forming material may be previously added to the regenerative substance, as disclosed in the official gazette of Japanese Patent Laid-Open (Kokai) Publication No. SHO 58-99696.
According to this conventional example, the addition of a crystalline nucleus forming material to a regenerative substance may prevent the regenerative substance from reaching a supercooled state. Thus, when the regenerative substance is cooled down to its freezing point, it begins to crystallize and radiate a latent heat.
In this case, however, the fact that the regenerative substance always has to be kept in a melting state at the melting point or higher temperatures is problematic.
At the same time, it is possible to intentionally maintain the supercooled state of the regenerative substance by not adding a crystalline nucleus forming material to the regenerative substance (thus preventing the regenerative substance from crystallizing even if the temperature lowers). By using this technology, we may apply a physical stimulus to the regenerative substance whenever necessary, and cause it to begin crystallization, to terminate the supercooled state, and to generate heat. As a means of attaining this purpose, a regenerative body in combination with a trigger is known, which is capable of applying a physical stimulus whenever necessary, and of keeping the regenerative substance in a supercooled state.
By using this trigger combined with a regenerative body, the supercooled state can be intentionally maintained even if the temperature lowers. Therefore, it is possible to cause the trigger to start functioning at any time to begin heat generation. Making use of this characteristic, it is possible to make a portable heat generating body by using the regenerative substance.
Examples of triggers for regenerative substances which have been suggested are: a trigger having a sharp metal tip which is intended to contact with the regenerative substance in a supercooled state to apply a physical stimulus, as disclosed in the official gazette of Japanese Patent Laid-Open (Kokai) Publication No. SHO 61-197921; and a trigger having a coil spring which is intended to contact with the regenerative substance in a supercooled state, in order to apply a physical stimulus to the regenerative substance when the regenerative substance is deformed by a force imposed from outside, as disclosed in the official gazette of Japanese Utility Model Laid-Open (Kokai) Publication No. HEI 3-25538.
However, the trigger for regenerative substances disclosed in the official gazette of Japanese Patent Laid-Open (Kokai) Publication No. SHO 61-197921 has a complicated construction by which to generate the physical stimulus. Other problems include the fact that the crystallization of the regenerative substance will not begin if the operation of the trigger is insufficient, and that the crystallization of the regenerative substance might accidentally begin if the trigger is mistakenly activated.
On the other hand, the trigger disclosed in the official gazette of Japanese Utility Model Laid-Open (Kokai) Publication No. HEI 3-25538 is problematic in that its construction is complicated, and in that it is therefore difficult to manufacture. Moreover, when transporting a regenerative body having this kind of trigger, vibrations or shocks occurring when it is being carried may cause the trigger to apply the physical stimulus to the regenerative substance. Accordingly, by the time the regenerative body is actually used, the generation of heat will have been depleted. This will impair the reliability of the regenerative body.
The present invention is intended to solve the above-mentioned problems which have arisen. The objective of this invention is to provide a trigger for regenerative substances which does not abruptly go into action due to forces arising out of shocks or vibrations during transportation, and to provide a trigger for regenerative substances which, when used, is capable of causing the regenerative substances to crystallize and to radiate a latent heat generated during the freezing process of the regenerative substances with absolute certainty. Another objective of this invention is to provide a reliable regenerative body which has such a trigger for regenerative substances.